The WAV crunched through the second wall dividing two adjacent tunnels. The thin layer hardly slowed her momentum. The HUD had guided her reluctant legs the first time, but the following times had been of her own volition.

  The worry in the back of her mind for a cave-in had reared its head too many times. She couldn't stop herself from crying wolf. Each impact made her cringe. Though proof of the opposite grew clearer with each new path she trailblazed, it wasn't doing the trick.

  If she still couldn't generate enough distance, a cave-in might become a necessity. It would also become a worse hazard than the hundreds of kilograms of killer fur still on her. Even rocks heavy enough to crush her WAV like a tin could only slow the Aud. It would dig through blockage like an excavator, devastatingly wily and determined.

  The HUD found new routes on the fly. It was the only thing directing her, and by extension, keeping her alive. She fired a different canister over her shoulder to disrupt the status quo. Cave-in it was.

  The bulbous orb shot down the tunnel, smacking into the Aud. The crocodile head rocked back. The jolt upset the contents, causing the orb to contract smaller than a pebble. It burst like a pustule, turning white-hot and spreading the melting slush into the Aud's fur.

  It snorted. The heat would've been easy to ignore. But it couldn't ignore the following combustion reaction. The space was normal one instant. Well, relatively speaking. It took only one more for an explosive blaze strong enough to send her flying to consume the tunnel behind her.

  The inevitable cave-in came like a second rain. Chunks of the ceiling, not ten meters above the two, crumbled from above. On the edge of the conflagration, her rear feed cut itself to protect her eyes. Thank the Directory for HUDs. Even then, her ears rang from being so close; the dinging felt stronger than a flash grenade's effects.

  Her ears kept track of the Aud when it called out. Not in pain. Knowing a part of everything humanity knew about the Aud let her catch the underlying rage. She'd be mad too if her prey was right before her eyes and vanished. But was that cheating? Not a chance.

  She was a good twenty meters from her initial position by the time she stopped tumbling. The tunnel ended five meters from her. The new rock wall was still compacting itself from the sudden repositioning.

  Unsure if it would start spilling out, she forced the suit's hydraulics to pick her up, create some distance. The Aud's screaming continued. She started again, ordering the HUD to perform an emergency survey on each subsystem.

  Damaged artificial musculature. Blunt trauma to the battery. She couldn't tell what that meant for the longevity of the suit despite working around WAVs all her career. The functionality of the battery core was a black box. She didn't bother thinking about it.

  It would continue working, or it wouldn't. Only a select few elite engineers were ever clued into their workings.

  The weapon systems in her right arm shut down after the power lines connecting to them got severed. It held her supply of flash grenades, something she disdained.

  At least the sonics were on the suit's left. Could the explosion have set off the other explosives stored on the left side? While the launcher had rattled its way off of optimal alignment, its payload remained.

  Surviving twice the original payload at point-blank range was out of the question. She received one too many shocks in too little time. She had to slow down, realizing she was gasping. Damn adrenaline. As likely to turn against her as it was to help her.

  The HUD was already injecting chemical cocktails to induce calm. It negated other aftereffects she wasn't in her right mind to consider. Light WAVs needed to last in isolated or hostile territory for extended periods.

  To enable that, they had internal mixing, injection, and storage facilities for synthesized hormones. They were the only class that did. She came to appreciate the added complexity of the suit fast. Not the best feeling in the world, though, pinpricks jabbing her bruised skin when she wasn't expecting it.

  Stress came back before long, even with the added contents to her bloodstream. She clenched and unclenched her hands to occupy them. Identifying that abnormal feeling of boredom took less time than before. Her cheeks flushed. It felt even more inappropriate.

  With the cave-in out of sight, the only activity left was to check on the drones. The one at the entrance was gone from her communication module. Before disappearing, it'd sent several detection signals, and later, a destruction one. She hadn't noticed in her mad scramble.

  They would take a while to find her. Even if the returning participants were more familiar with the tunnels, she had the HUD. But that advantage would be null if she didn't get to making enough distance between her and the screaming Aud at her back. It wouldn't stop. That'd draw others in the nearby tunnels like a beacon.

  At the next fork, she made a new route. The skewed battleground between the wall's integrity and her suit did put up more noticeable resistance. She stumbled through once it resolved in her favor.

  On the other side was a skeleton. Knocked over from her entry, it splayed across the tunnel floor. The pose looked natural. Like something she would've done, stretching after waking up

  The cavern's ecosystem and time had weathered away any identifiable features. No technology or clothes. The skull jaw slackened, popping free and clattering down. It caught on the clavicle. She took a moment to look it over, finding nothing noteworthy.

  Ignoring the jawbone's pendulum swing while doing so, of course. It was odd this was only the first corpse she'd found, but the others had probably met their proper ends. Crushed underhoof by passing Aud over the generations. No reason to linger.

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  "Notice: Tertiary checkpoint marked. Estimation: ETA: Twenty minutes with current timed progress."

  Good. Even after all the panicked maneuvering, the HUD hadn't strayed as she had. One of the drone feeds went blank. Frowning, she brought up the adjacent drone's feed.

  Orders to investigate were discreetly passed through the connection. It dashed like a jackal along the walls, well-oiled servos providing no friction. The resonant hums of the tunnels were the only companions on both ends.

  While the first investigated, she sent the second to double back to check on the yellow. It reached its destination sooner, locating the trail of destruction and following it. The Aud had made its warpath easy to find.

  Two more yellows had joined it, growling at it while her former pursuer fruitlessly dug. With no changes at the scene, she set it back to scouting the upcoming greater tunnel.

  It'd been long enough in the Lesser Tunnel System. If another beast tailed her again, she had no guarantees the HUD could draw a continuous escape path like before. Her WAV's smaller size only did so much to help with that.

  She was a mouse in a maze, hunted by cats that could break through the barriers only in place to limit her movements. She would only last until tunnel walls she couldn't break through trapped her.

  Two greater tunnels were far to the west, and beneath her, based on the map. She noted that the map updated to display the tunnel she'd caused the cave-in at. The natural subterranean architecture broke there. She'd be lying if she didn't say that left her satisfied.

  Pa-5 decided to head for the one dozens of meters below her. She wanted to come back out into the Gaiss Hollow at some point. Not begin a one-woman exploratory survey. After informing the HUD of that, she sat back and let it puzzle out the next series of routes. Waiting in place was counterproductive, so she continued onward at a moderate pace.

  After the previous encounter, leaving her back unchecked for too long left her wary. This newfound paranoia spared her twice when she hid from an approaching growl or noise. Her breath caught worse the second time when she realized she was mere meters from an unaware blue-fur.

  She almost cried when it settled down right in the center of the tunnel for a nap. She waited a few minutes, debating whether to make a distraction. The environment saved her the trouble: a far-off clatter aroused its interest.

  She waited until the predator was out of sight, then waited longer still. Longer after that. Only after her knees began to cramp from the WAV's crouching position did she glance outside her hidey-hole. She did shed a tear from relief.

  She wasn't far from reentering the greater tunnels by then. Enough time had passed in silence that she risked unlatching the launcher on her right arm. It was useless if left be, and performing field repairs wasn't her specialty.

  Especially not with the suit's clumsy fingers, and she couldn't exit the suit without external help. Not that she'd choose to, here. Emptying the launcher, she discarded it under a pile of boulders pushed up against one of the walls. She wouldn't risk an inquisitive Aud discovering it and then alerting the others. They'd hunt her like bloodhounds.

  If the suit wasn't airtight and filtered both air expelled and taken in, they'd already be after her. Filtering her outgoing scent saved her an endless chase. Stopping anything harmful in the air from getting in kept her on her feet without the need for more drugs.

  The remaining flash grenades went in one of the leg compartments. She kept one at the ready in her palm, fingering the cylinder. Without the launcher, she couldn't prime it conventionally. Throwing it hard enough to breach the casing would work in its place.

  "Estimation: Twelve hours since last matter and fluid ingestion."

  Only then did her resentful stomach flare up. Was it her imagination, or did its grumble echo inside the suit? Her throat followed suit, finding the strength to become parched in a second. She wanted to curse her traitorous body.

  Yes, she was hungry and thirsty. Soon she'd feel tired too, once she cut into her circadian rhythm. Tough. The only option was to continue forward. The lack of food within reach also made the situation more bearable, as did the convenient lack of a bunk. The suit took care of her immediate needs, injecting two more cocktails.

  The first quieted her stomach as the signals moving between her brain and digestive system got hijacked. It believed the body had received its sustenance. The second had something mixed with caffeine. It killed whatever drowsiness she'd accumulated.

  Along with the aftereffects from high doses of liquid sun, the new withdrawals wouldn't make her recovery anything pretty. Again, if she made it back.

  She could at least deal with her thirst. The greater and lesser tunnels were incredibly damp. Which, among other things, made them a perfect breeding ground for bacteria and other ick.

  They were also chock full of water, not immediately harvestable. Her WAV's collection and purification faculties had been active since the quaternary checkpoint. A nozzle inserted itself into a corner by her lips, prodding light to be let inside.

  The cool, refreshing rush woke her up even more than the caffeine. She sucked greedily, taking the chance to fill her stomach, even if it was on fluids alone. Even if it emptied the accumulated reserve that she might need later.

  That such an action felt normal felt off. And that such a thing felt off felt, well, off as well. Proper normal. What did the earlier generations' version of normal look like? The clarity managed to calm her nerves a little more, where the hormones failed.

  She wanted to growl when the drone scouting the greater tunnel below provided grim news. At least one Aud was present every two hundred meters within its twisting bowels. Most of them were low tiers, but all they needed was a single alerting cry to come swarming.

  She shivered, the wall of death and fur her drone had recorded at the failing fort still fresh in memory. She wondered if the engineers in the underground garage had had a chance to fight back. To get into suits of their own before they became torn ribbons.

  The one thing she wondered at was the sitesman. Where had he been? Even during the fitting process for the suicide runners, he'd observed via transmission. His office was at the center of the fort, but the sector it was in was one of the first to be overrun by the dropping Aud.

  Her barracks hadn't even been on the edge of it, and what resistance they'd put up lasted minutes at best. Even outside the fort, she'd been unable to see the towering ceilingscraper. Increasing the distance didn't change things. The safest assumption was that one too many impacts had knocked it over.

  So had the sitesman survived then? Was he in an underground bunker? Or were her thoughts driven by wishful thinking she entertained, wishing she could verify that she and whoever still had a beating heart amongst messengers weren't the only ones left?

  She ignored the dark part of it whispering in her ear, claiming there were none left aside from here. And that soon, there'd actually be none.